Field of the Invention
The present invention relates to a method and system for inspecting defects, and more particularly to a method and system for fast inspecting defects which decreases false rate of defect inspection.
Description of the Prior Art
Defect inspection in the semiconductor device has always been one of important issues in semiconductor manufacturing process. Referring to FIG. 1, a conventional method for inspecting defects is achieved by obtaining a scanned image, e.g. an SEM (scanning electron microscope) image of a specimen such as a semiconductor device (S11) and identifying defects on the surface of the specimen within the scanned image (S12). Since the scanned data is of extremely enormous data volume and often larger than 20 TB (tera-byte), the scanned data would be discarded after defect inspection (S13). In the case of requiring further verification for defects (S14), then return to step S11 and the specimen is rescanned for defect analysis. Referring to FIG. 2, to be brief, the conventional method for inspecting defects alternates between specimen scanning and data analysis.
Some identified suspicious defects might be not real defects and a false rate is used for representing the accuracy of defect inspection. The false rate has kept increasing due to sustained trend of minimized semiconductor manufacturing process and tremendously increased scanned data. The false rate may be improved by enhancing scanning resolution of E-beam inspection tools and rescanning all of regions of interest in the same specimen; however, the scanning time and scanned data would be greatly increased due to the enhanced scanning resolution of E-beam inspection tools. In addition to increased inspection time, rescanning might also encounter certain issues, such as missing real defects and misjudging non-defects, caused by varied scanning conditions. For example, the charge condition of the surface of the specimen might be changed at first E-beam scanning and results in variation in the scanned image obtained at the second E-beam scanning and biased result of defect inspection.
To sum up, it is now a current goal to lower false rate of defect inspection.